National Transportation Safety Board (NTSB) investigators are traveling to Paraguay to assist in the investigation of a Robinson R44 II helicopter crash on Sunday. Three people died as a result of the crash, including the pilot and Lino Cesar Oviedo, who was a candidate for president of Paraguay.

According to Paraguay’s civil aviation authority, all three were found dead when the helicopter wreckage was discovered. The investigators are still unclear as to what caused the crash. The crash reportedly occurred during a trip along the campaign trail for Oviedo.